Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$141.73	6.820%	$151.396	$151.40	$151.40	$151.40
Purchase #2	$74.48	5.606%	$78.6553	$78.66	$78.65	$78.70
Purchase #3	$94.57	13.466%	$107.3048	$107.30	$107.30	$107.30
Purchase #4	$64.57	3.588%	$66.8868	$66.89	$66.90	$66.90
Purchase #5	$199.92	5.258%	$210.4318	$210.43	$210.45	$210.40
Purchase #6	$187.93	13.401%	$213.1145	$213.11	$213.10	$213.10
Purchase #7	$95.66	9.553%	$104.7984	$104.80	$104.80	$104.80
7 purchase totals =	$858.86		$932.5876	$932.59	$932.60	$932.60